You have a field on the Contact object that is visible to the Marketo Sync user, but updates to that field are not being passed to the record in Marketo. The field is not a lookup or formula field, and the matching field on the Lead object does sync.
Certain fields in Salesforce are ignored by the Marketo/SFDC sync. Ignored fields are listed by object below.
Who This Solution Applies To
Customers with Salesforce integrations